Kakon Omma Petrôseôs is an attack spell which releases a beam of light from the fingers, petrifying all living and non-living beings in contact with it. The beam is also capable of being released from one's eye in a skilled mage, a reference to the Basilisk invoked in the spell.

Due to the concentrated nature of the attack, it has a smaller effective range compared to Pnoē Petras , but it is capable of penetrating magic shields. The beam itself is also physically destructive, shown to be able to easily cut through wood.